1. Field of the Invention
The present invention is directed to an X-ray examination apparatus which has a magazine for an unpaked and unexposed X-ray film material and means for transporting the film from the magazine to an exposure station and the means for transporting includes a housing which is sealed to the magazine so as to be impervious to light.
2. Prior Art
X-ray examination apparatuses, which have a magazine for either roll film or sheet film and means for transporting the film, which is free from a protective X-ray cassette, from the magazine to an exposure or photographic station and then to a storage magazine, are generally known. Examples of these X-ray examination apparatuses are disclosed in U.S. Pat. Nos. 3,415,988 and 3,553,453 as well as in German Offenlegungsschrift No. 2,031,386, which corresponds to United States patent application Ser. No. 147,736. In the X-ray examination apparatus of the above-mentioned type, the X-ray film material must be protected during its movement on the transport path not only from the incidents of light but also from electrostatic charges. The emulsion layer of the X-ray film has such a great electrical resistance, that it will become electrostatically charged during a rapid transport whether it is by sliding or rolling friction. The resulting electrostatic charges accummulate until they exceed the disruptive or dielectric strength of the film material. During the following electrical discharge, conversion or transformation changes in the emulsion layer will occur along the discharge channel or path. The usual discharge panel or path will have a dendroid configuration and is clearly visible after development of the film material which will exhibit dendriform exposure marks, which will have the configuration similar to streaks of lightening. These exposure marks, which are produced on the film at the discharge paths or channels, will be superimposed on the examination image and in some instances, interfer with the proper diagnosis of the X-ray image.
In order to rapidly break down the electrostatic charges or to restrict them to noncritical values, it has been previously proposed that the air within the region of the transport paths for the film material be ionized. However, the high voltage discharge paths, which are suitable as ion sources, also produce optical light, and they must therefore be installed so that they are either shielded from the film material which is transported passed the discharge paths or be provided with light traps. The provision of the shields or the light traps increases the cost of the apparatus.